Well, ideally in a CQB "Assault" situation, you wouldn't be breaching with ANY pistol unless you were holding the shield for the other assaulters to operate behind.
But, in interest of the question asked, you have to assume a missfire is one of two things immediately:
1) The round in question
2) assume the weapon is the problem, in which case doing anything else with it is pointless.
Ideally you would know your pistol and would know if something was wrong, know that it will always feed your ammo, that it will always go bang and therefore the missfire is the round in question.
In that case, I was taught in Combat Focus to draw the weapon back to High Chest Center
and with my off hand, rack the slide, with the off hand over the top of the slide, to clear the round and chamber the new round.
With the weapon at High Chest Center you have your elbows out, which allows for more control of the weapon and allows you to move without running into anything.
The same process is used for an empty reload, though you try to never shoot a weapon dry, or you perform the same action with a tactical or "hot" reload without the charging of the slide.
Then you press out from High Chest Center and back on target.
I can highly recommend reading Rob Pincus' book Combat Focus
and watching the videos that he has made and put out online.
Hope that helps -